1. Field of the Invention
The present invention relates to a shift control system for a transmission mounted on a working vehicle such as a lawn mower or lawn tractor and having a backward/forward drive changeover device and a stepless change speed device.
2. Description of the Related Art
A working vehicle having such a shift control system, particularly where a friction type change speed device is used as the stepless change speed device, additionally includes a backward/forward drive changeover device since the stepless change speed device alone cannot effect a changeover between forward drive and backward drive. This type of working vehicle is disclosed in Japanese Patent Publication Kokai No. 2-209651, for example. In the working vehicle disclosed therein, running speed is increased or decreased by a friction type stepless change speed device utilizing a taper cone, and a changeover between forward drive and backward drive is effected by a backward/forward drive changeover device. The vehicle includes a shift lever and a switch lever for controlling the respective devices. po When the shift lever is operated to a maximum extent, the same maximum speed is available for backward drive as well as forward drive. However, the vehicle need not run at high speed backward, and the known shift control system is not considered to realize an optimal control.